Funds are requested to upgrade an existing GN500 nmr spectrometer. Specific components to replace are: the aging Nicolet 1280 computer with a SUN data acquisition system; the low sensitivity proton probe with a high sensitivity probe; and the built-in decoupler with a sophisticated broad- band decoupler. This facility is equally shared by 4 research groups: Professor Baldwin (Biochemistry), Boxer (Chemistry), Huestis (Chemistry) and McConnell (Chemistry). Professor Baldwin's research involves the mechanism of protein folding using pulse-labeling of water accessible amide protons. Studies of small peptides and larger proteins modified by site-specific mutagenesis are proposed. Professor Boxer's research involves studies of electrostatics and dynamics in recombinant human and sperm whale myoglobins. A wide range of experimental methods is used to test specific proposals concerning the mechanism of access and exit of diatomic ligands to the heme pocket. Structural characterization by 2D nmr methods and proton exchange kinetics are central to this project. Professor Huestis's research involves studies of interactions between proteins and lipid bilayers. Nmr provides a non-invasive, sensitive method to monitor peptide association with the hydrophobic domain of cell membranes and to examine protein-membrane interactions in normal and pathological states. Professor McConnell's research involves studies of antibody-hapten interactions primarily involving monoclonal antibodies directed against spin-label haptens. The nmr spectrum of the complex is assigned by a combination of deuteration and line broadening to provide a detailed view of the antibody combining site for a collection of antibodies to the same hapten. With this structural information in hand new antibodies are designed by mutagenesis experiments to test structural models and potentially to increase antibody hapten affinity.